Improvement in photographic plates



UNITED STATES PATENT OFFICE FREDERICK H. POWELL AND PHILIP LEHNEN, OFAUBURN, NEW YORK.

IMPROVEMENT IN PHOTOGRAPHlC PLATES.

Specification forming part of Letters Patent No. March 'proof, andcoated on the back with an oil and varnish paint, and on the face withone or more coats of baking japan or varnish, each coat being baked inan oven. The paper employed may be of any convenient size and thickness,and may be manufactured so as to be heavier and better liable to sink inthe bath by adding clay, barytes, or other heavy substance to the pulp.The paper is first made water-proof either with oil or with a mixture ofoils and turpentine or benzine, or any kind of varnish. A coat of anysuitable oil or varnish paint is put on the back of the paper toincrease the weight of the same so that it will sink readily in thebath. The paper is then put into an oven and baked until hard, thebaking operation commencing at a low degree of heat. The other side orface of the paper is then coated with one or more layers of baking japanor varnish, according to the finish required, and each coat baked asbefore,

178,380, dated June 6, 1876; application filed 13,1876.

any desired color or tint being imparted t1 the face surface, accordingto the different ob jects towhich the paper is applied. A pho tographicplate made from paper so preparet sinks readily in the bath is lighterthan flli metallic plates, so that photographs madr thereon may be sentat less expense througl the mail, being cheaper than the metalli1plates; and also more durable, as the plate, Ol account of itsflexibility, does not crack whei bent.

Having thus described our invention, w claim as new and desire to secureby Letter: Patent- 1. An improved plate forphotographs 0: signs made ofwater-proof paper, having coat of paint on the back, and one or lllOItcoats of baking japan or varnish on the face and hardened, as and forthe purpose se forth.

2. The process herein described of prepar ing paper for photograph andsign plates, con sisting in first waterproofing the paper, the] coatingthe back with a paint, and baking i in oven till hard, then coating theface witl one or more layers of baking japan or varnish and then bakingsuch final coat to hardnes to obtain the required finish, substantiallya; set forth.

FREDK. H. POWELL. PHILIP LEHNEN.

Witnesses:

S. S. MOTT, F. S. DAY.

